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Journal of Biomechanics

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https://www.readbyqxmd.com/read/28342532/shear-scaling-based-approach-for-irreversible-energy-loss-estimation-in-stenotic-aortic-flow-an-in-vitro-study
#1
Utku Gülan, Christian Binter, Sebastian Kozerke, Markus Holzner
Today, the functional and risk assessment of stenosed arteries is mostly based on ultrasound Doppler blood flow velocity measurements or catheter pressure measurements, which rely on several assumptions. Alternatively, blood velocity including turbulent kinetic energy (TKE) may be measured using MRI. The aim of the present study is to validate a TKE-based approach that relies on the fact that turbulence production is dominated by the flow's shear to determine the total irreversible energy loss from MRI scans...
March 12, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28342531/sensitivity-of-medial-and-lateral-knee-contact-force-predictions-to-frontal-plane-alignment-and-contact-locations
#2
Christopher M Saliba, Scott C E Brandon, Kevin J Deluzio
Musculoskeletal models are increasingly used to estimate medial and lateral knee contact forces, which are difficult to measure in vivo. The sensitivity of contact force predictions to modeling parameters is important to the interpretation and implication of results generated by the model. The purpose of this study was to quantify the sensitivity of knee contact force predictions to simultaneous errors in frontal plane knee alignment and contact locations under different dynamic conditions. We scaled a generic musculoskeletal model for N=23 subjects' stature and radiographic knee alignment, then perturbed frontal plane alignment and mediolateral contact locations within experimentally-possible ranges of 10° to -10° and 10 to -10mm, respectively...
March 12, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28318604/comparison-of-whole-body-vertical-stiffness-and-leg-stiffness-during-single-leg-hopping-in-place-in-children-and-adults
#3
Matthew Beerse, Jianhua Wu
In the hopping literature, whole-body vertical stiffness and leg stiffness are used interchangeably, due to most of the movement occurring in the vertical direction. However, there is some anterior/posterior movement of the center of mass and displacements of the foot during hopping in place in both children and adults. Further it is not understood if leg stiffness show a similar pattern as whole-body vertical stiffness when increasing hopping frequency. The purpose of this study was to test if whole-body vertical stiffness and leg stiffness are different during single-leg hopping in-place in children and adults, across a range of frequencies...
March 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28320506/unexpected-walking-perturbations-reliability-and-validity-of-a-new-treadmill-protocol-to-provoke-muscular-reflex-activities-at-lower-extremities-and-the-trunk
#4
Tilman Engel, Juliane Mueller, Stephan Kopinski, Antje Reschke, Steffen Mueller, Frank Mayer
Instrumented treadmills offer the potential to generate standardized walking perturbations, which are particularly rapid and powerful. However, technical requirements to release adequate perturbations regarding timing, duration and amplitude are demanding. This study investigated the test-retest reliability and validity of a new treadmill perturbation protocol releasing rapid and unexpected belt perturbations to provoke muscular reflex responses at lower extremities and the trunk. Fourteen healthy participants underwent two identical treadmill walking protocols, consisting of 10 superimposed one-sided belt perturbations (100ms duration; 2m/s amplitude), triggered by a plantar pressure insole 200ms after heel contact...
March 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28314563/a-biomechanical-approach-to-the-analysis-of-methods-and-procedures-of-bariatric-surgery
#5
Emanuele Luigi Carniel, Alessandro Frigo, Chiara Giulia Fontanella, Giulia Maria De Benedictis, Alessandro Rubini, Luca Barp, Gioela Pluchino, Beatrice Sabbadini, Lino Polese
Bariatric surgery includes a variety of procedures that are performed on obese people and aim at decreasing the intake of food and calories. This goal is usually pursued by reducing stomach capacity and/or absorbing capability. Adjustable gastric banding is the most common and successful operation. In general, bariatric surgical procedures are effective, but are often associated with major complications. Surgical procedure and post-surgical conformation of the stomach are usually defined on clinical and surgical basis only...
March 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285744/dynamic-time-warping-compared-to-established-methods-for-validation-of-musculoskeletal-models
#6
Martin Gaspar, Bastian Welke, Frank Seehaus, Christof Hurschler, Michael Schwarze
By means of Multi-Body musculoskeletal simulation, important variables such as internal joint forces and moments can be estimated which cannot be measured directly. Validation can ensued by qualitative or by quantitative methods. Especially when comparing time-dependent signals, many methods do not perform well and validation is often limited to qualitative approaches. The aim of the present study was to investigate the capabilities of the Dynamic Time Warping (DTW) algorithm for comparing time series, which can quantify phase as well as amplitude errors...
March 4, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28318605/achilles-tendon-moment-arm-length-is-smaller-in-children-with-cerebral-palsy-than-in-typically-developing-children
#7
Barbara M Kalkman, Lynn Bar-On, Francesco Cenni, Constantinos N Maganaris, Alfie Bass, Gill Holmes, Kaat Desloovere, Gabor J Barton, Thomas D O'Brien
When studying muscle and whole-body function in children with cerebral palsy (CP), knowledge about both internal and external moment arms is essential since they determine the mechanical advantage of a muscle over an external force. Here we asked if Achilles tendon moment arm (MAAT) length is different in children with CP and age-matched typically developing (TD) children, and if MAAT can be predicted from anthropometric measurements. Sixteen children with CP (age: 10y 7m±3y, 7 hemiplegia, 12 diplegia, GMFCS level: I (11) and II (8)) and twenty TD children (age: 10y 6m±3y) participated in this case-control study...
March 3, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285745/experimental-measurements-and-mathematical-modeling-towards-quantification-of-brain-swelling-stress
#8
Stelios Angeli, Triantafyllos Stylianopoulos
Traumatic brain injury results in brain tissue swelling which can be a life threatening condition due to skull confinement. While previous efforts successfully measured the exhibited volume change in brain tissue swelling, no data exist to provide information about the exhibited stresses. In this study, confined compression mechanical testing was employed to measure swelling stress in murine brain tissue samples by varying the ionic concentration of the bathing solutions. Subsequently, computer simulations of the experimental protocol were employed to confirm a triphasic mathematical model describing the effect and provide insights into the experimental data...
March 3, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285747/effect-of-the-ventricular-folds-in-a-synthetic-larynx-model
#9
Stefan Kniesburges, Veronika Birk, Alexander Lodermeyer, Anne Schützenberger, Christopher Bohr, Stefan Becker
Within the human larynx, the ventricular folds serve primarily as a protecting valve during swallowing. They are located directly above the sound-generating vocal folds. During normal phonation, the ventricular folds are passive structures that are not excited to periodical oscillations. However, the impact of the ventricular folds on the phonation process has not yet been finally clarified. An experimental synthetic human larynx model was used to investigate the effect of the ventricular folds on the phonation process...
February 28, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28325584/development-of-a-surrogate-model-based-on-patient-weight-bone-mass-and-geometry-to-predict-femoral-neck-strains-and-fracture-loads
#10
Mark Taylor, Egon Perilli, Saulo Martelli
Osteoporosis and related bone fractures are an increasing global burden in our ageing society. Areal bone mineral density assessed through dual energy X-ray absorptiometry (DEXA), the clinically accepted and most used method, is not sufficient to assess fracture risk individually. Finite element (FE) modelling has shown improvements in prediction of fracture risk, better than aBMD from DEXA, but is not practical for widespread clinical use. The aim of this study was to develop an adaptive neural network (ANN)-based surrogate model to predict femoral neck strains and fracture loads obtained from a previously developed population-based FE model...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28318603/rupture-risk-in-abdominal-aortic-aneurysms-a-realistic-assessment-of-the-explicit-gpu-approach
#11
V Strbac, D M Pierce, B Rodriguez-Vila, J Vander Sloten, N Famaey
Accurate estimation of peak wall stress (PWS) is the crux of biomechanically motivated rupture risk assessment for abdominal aortic aneurysms aimed to improve clinical outcomes. Such assessments often use the finite element (FE) method to obtain PWS, albeit at a high computational cost, motivating simplifications in material or element formulations. These simplifications, while useful, come at a cost of reliability and accuracy. We achieve research-standard accuracy and maintain clinically applicable speeds by using novel computational technologies...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28314562/intermittent-vibration-protects-aged-muscle-from-mechanical-and-oxidative-damage-under-prolonged-compression
#12
Sing Wan Wong, Brian Chun Ho Cheung, Bruce Tak Keung Pang, Ateline Kwong, Anna Chung, Kenneth Ka Ho Lee, Arthur Fut Tak Mak
Deep tissue pressure ulcers, a serious clinical challenge originating in the muscle layer, are hardly detectable at the beginning. The challenge apparently occurs in aged subjects more frequently. As the ulcer propagates to the skin surface, it becomes very difficult to manage and can lead to fatal complications. Preventive measures are thus highly desirable. Although the complex pathological mechanisms have not been fully understood, prolonged and excessive physical challenges and oxidative stress are believed to be involved in the ulcer development...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28302314/a-new-measure-of-trip-risk-integrating-minimum-foot-clearance-and-dynamic-stability-across-the-swing-phase-of-gait
#13
Brian W Schulz
Minimum toe clearance (MTC) is thought to quantify the risk of the toe contacting the ground during the swing phase of gait and initiating a trip, but there are methodological issues with this measure and the risk of trip-related falls has been shown to also be associated with gait speed and dynamic stability. This paper proposes and evaluates a new measure, trip risk integral (TRI), that circumvents many issues with MTC as typically calculated at a single point by considering minimum foot clearance across the entire swing phase and taking into account dynamic stability to estimate risk of falling due to a trip rather than risk of the foot contacting the floor...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285748/a-modelling-approach-demonstrating-micromechanical-changes-in-the-tibial-cemented-interface-due-to-in-vivo-service
#14
Priyanka Srinivasan, Mark A Miller, Nico Verdonschot, Kenneth A Mann, Dennis Janssen
Post-operative changes in trabecular bone morphology at the cement-bone interface can vary depending on time in service. This study aims to investigate how micromotion and bone strains change at the tibial bone-cement interface before and after cementation. This work discusses whether the morphology of the post-mortem interface can be explained by studying changes in these mechanical quantities. Three post-mortem cement-bone interface specimens showing varying levels of bone resorption (minimal, extensive and intermediate) were selected for this study Using image segmentation techniques, masks of the post-mortem bone were dilated to fill up the mould spaces in the cement to obtain the immediately post-operative situation...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285743/relationships-of-the-group-velocity-of-the-time-reversed-lamb-wave-with-bone-properties-in-cortical-bone-in-vitro
#15
Kang Il Lee, Suk Wang Yoon
The present study aims to investigate the feasibility of using the time-reversed Lamb wave as a new method for noninvasive characterization of long cortical bones. The group velocity of the time-reversed Lamb wave launched by using the modified time reversal method was measured in 15 bovine tibiae, and their correlations with the bone properties of the tibia were examined. The group velocity of the time-reversed Lamb wave showed significant positive correlations with the bone properties (r=0.55-0.81). The best univariate predictor of the group velocity of the time-reversed Lamb wave was the cortical thickness, yielding an adjusted squared correlation coefficient (r(2)) of 0...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28284667/center-of-pressure-and-center-of-mass-behavior-during-gait-initiation-on-inclined-surfaces-a-statistical-parametric-mapping-analysis
#16
Marcus Fraga Vieira, Ademir Alves de Brito, Georgia Cristina Lehnen, Fábio Barbosa Rodrigues
This study analyzed gait initiation (GI) on inclined surfaces with 68 young adult subjects of both sexes. Ground reaction forces and moments were collected using two AMTI force platforms, of which one was in a horizontal position and the other was inclined by 8% in relation to the horizontal plane. Departing from a standing position, each participant executed three trials in the following conditions: horizontal position (HOR), inclined position at ankle dorsi-flexion (UP), and inclined position at ankle plantar-flexion (DOWN)...
February 27, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28279400/the-effects-of-groove-height-and-substrate-stiffness-on-c-elegans-locomotion
#17
Lipika Parida, Udita Uday Ghosh, Venkat Padmanabhan
The physical environment surrounding an animal has a significant impact on its behavior. The nematode Caenorhabditis elegans (C. elegans) has proved to be an excellent choice for understanding the adaptability of organisms crawling on soft surfaces. In this work, we investigate the modulation of C. elegans' behavioral kinematics in response to changes in the stiffness of the substrate and study the effect of grooves incised by the worms on their locomotion speed and efficiency. We measure the height of the grooves created by the animals on surfaces with different rigidity using confocal microscopy...
February 23, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28302315/the-development-and-concurrent-validity-of-a-real-time-algorithm-for-temporal-gait-analysis-using-inertial-measurement-units
#18
E Allseits, J Lučarević, R Gailey, V Agrawal, I Gaunaurd, C Bennett
The use of inertial measurement units (IMUs) for gait analysis has emerged as a tool for clinical applications. Shank gyroscope signals have been utilized to identify heel-strike and toe-off, which serve as the foundation for calculating temporal parameters of gait such as single and double limb support time. Recent publications have shown that toe-off occurs later than predicted by the dual minima method (DMM), which has been adopted as an IMU-based gait event detection algorithm.In this study, a real-time algorithm, Noise-Zero Crossing (NZC), was developed to accurately compute temporal gait parameters...
February 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28291516/a-practical-solution-to-reduce-soft-tissue-artifact-error-at-the-knee-using-adaptive-kinematic-constraints
#19
Brigitte M Potvin, Mohammad S Shourijeh, Kenneth B Smale, Daniel L Benoit
Musculoskeletal modeling and simulations have vast potential in clinical and research fields, but face various challenges in representing the complexities of the human body. Soft tissue artifact from skin-mounted markers may lead to non-physiological representation of joint motions being used as inputs to models in simulations. To address this, we have developed adaptive joint constraints on five of the six degree of freedom of the knee joint based on in vivo tibiofemoral joint motions recorded during walking, hopping and cutting motions from subjects instrumented with intra-cortical pins inserted into their tibia and femur...
February 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28285746/single-and-multiple-step-balance-recovery-responses-can-be-different-at-first-step-lift-off-following-lateral-waist-pull-perturbations-in-older-adults
#20
Masahiro Fujimoto, Woei-Nan Bair, Mark W Rogers
An inability to recover lateral balance with a single step is predictive of future falls in older adults. This study investigated if balance stability at first step lift-off (FSLO) would be different between multiple and single stepping responses to lateral perturbations. 54 healthy older adults received left and right waist-pulls at 5 different intensities (levels 1-5). Crossover stepping responses at and above intensity level 3 that induced both single and multiple steps were analyzed. Whole-body center of mass (COM) and center of pressure (COP) positions in the medio-lateral direction with respect to the base of support were calculated...
February 21, 2017: Journal of Biomechanics
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